Dielectric Properties of Polypropylene by Deashing Method for DC Polymer Film Capacitors

In this paper, a novel deashing method was proposed to prepare polypropylene (PP) materials with different ash contents (80 ~ 560 ppm). Effects of the ash on dielectric and energy storage characteristics of PP in polymer film capacitors were studied. The experimental results reveal that a low content of ash will help to improve the dielectric properties. Compared to the sample with 560 ppm of ash content, the PP film with 60 ppm ash possesses a lower DC conductivity (1.85×10-14 S/m). After the purification, the decline of the ash content in PP prevents the local electric field distortion and enhances the breakdown strength, which is beneficial for the improvement of the discharge energy density. Meanwhile, the reduction in the number of carriers ionized by the ash weakens the transport behavior and reduces the conductivity. It is concluded that the PP with high purity shows a great potential in polymer film capacitors